Figure 4.

QnrB promotes plasmid propagation in a manner that is independent of DNA gyrase protection. E. coli strains harboring pQE80L (empty vector), pQE‐qnrB or pQE‐qnrBΔcoil3 were cultured to an OD₆₀₀ of 0.6 in LB at 25°C, and then 0.5 mM IPTG and/or 5 mg/l CIP was added. After culture for 1 h, the plasmids were isolated and dissolved in 50 μl of water. Equal volumes were analyzed by gel electrophoresis. M, DNA marker.